Ground vehicles such as automobiles and trucks propelled by internal combustion engines are typically controlled by an operator accelerator pedal which is directly mechanically linked to an engine speed controlling device such as a throttle body or fuel injection pump. Recently, so called fly-by-wire systems have been considered for automotive applications which replace the accelerator pedal to throttle body mechanical linkage with an electrical control system in which the operator input is an electrical signal to a controller which is processed, amplified and output to an actuator or motor for positioning the vehicle throttle. Fly-by-wire systems provide the advantage of accepting operator speed demand as only one of a number of input parameters which determine the ultimate positioning of the throttle and thus permit overriding or modifying a driver input if safety or performance considerations so require. Typical systems requiring throttle intervention include traction control, cruise control and engine speed governing.
Although fly-by-wire techniques have found acceptance in aerospace and certain industrial applications, its penetration in the automotive industry has been limited due to countervailing considerations of reliability and economy.
A compromise approach to vehicle throttle control thus employs conventional mechanical linkage between the accelerator pedal and the throttle body in combination with electromechanical devices which alter the linkage geometry to permit the implementation of traction control and other features while retaining proven throttle control techniques. Although such systems are gaining acceptance, they tend to be slow to respond to rapid changes in input parameters and, in traction control applications, can require the application of vehicle brakes during periods of operator acceleration demand.
It will be apparent from a reading of the specification that the present invention may be advantageously utilized with throttle controls for internal combustion engines intended for many different applications. However, the invention is especially useful when applied to the accelerator pedal-throttle body linkage of an automotive vehicles, and will be described in connection therewith.